Add new user option 'read-minibuffer-restore-windows'

* doc/lispref/minibuf.texi (Text from Minibuffer): Document it
(bug#45072).

* lisp/cus-start.el (standard): Add.

* src/minibuf.c (syms_of_minibuf): New variable
'read-minibuffer-restore-windows'.

doc/lispref/minibuf.texi

@@ -469,6 +469,18 @@ If @var{default} is a non-@code{nil} list, the first element of the
 list is used in the prompt.
 @end defun
 
+@defvar read-minibuffer-restore-windows
+If this option is non-@code{nil} (the default), getting input from the
+minibuffer will restore, on exit, the window configurations of the frame
+where the minibuffer was entered from and, if it is different, the frame
+that owns the minibuffer window.  This means that if, for example, a
+user splits a window while getting input from the minibuffer on the same
+frame, that split will be undone when exiting the minibuffer.
+
+If this option is @code{nil}, no such restorations are done.  Hence, the
+window split mentioned above will persist after exiting the minibuffer.
+@end defvar
+
 @node Object from Minibuffer
 @section Reading Lisp Objects with the Minibuffer
 @cindex minibuffer input, reading lisp objects

etc/NEWS

@@ -178,6 +178,9 @@ behavior, which mixed these two, can be approximated by customizing
 'minibuffer-follows-selected-frame' to a value which is neither nil
 nor t.
 
++++
+** New user option 'read-minibuffer-restore-windows'.
+
 +++
 ** New system for displaying documentation for groups of functions.
 This can either be used by saying 'M-x shortdoc-display-group' and

lisp/cus-start.el

@@ -431,6 +431,7 @@ Leaving \"Default\" unchecked is equivalent with specifying a default of
 	      "21.1"
               :set minibuffer-prompt-properties--setter)
 	     (minibuffer-auto-raise minibuffer boolean)
+             (read-minibuffer-restore-windows boolean "28.1")
 	     ;; options property set at end
 	     (read-buffer-function minibuffer
 				   (choice (const nil)

src/minibuf.c

@@ -689,12 +689,15 @@ read_minibuf (Lisp_Object map, Lisp_Object initial, Lisp_Object prompt,
     call1 (Qpush_window_buffer_onto_prev, minibuf_window);
 
   record_unwind_protect_void (minibuffer_unwind);
-  record_unwind_protect (restore_window_configuration,
-			 list3 (Fcurrent_window_configuration (Qnil), Qt, Qt));
+  if (read_minibuffer_restore_windows)
+    record_unwind_protect (restore_window_configuration,
+			   list3 (Fcurrent_window_configuration (Qnil),
+				  Qt, Qt));
 
   /* If the minibuffer window is on a different frame, save that
      frame's configuration too.  */
-  if (!EQ (mini_frame, selected_frame))
+  if (read_minibuffer_restore_windows &&
+      !EQ (mini_frame, selected_frame))
     record_unwind_protect (restore_window_configuration,
 			   list3 (Fcurrent_window_configuration (mini_frame),
 				  Qnil, Qt));
@@ -2527,6 +2530,15 @@ for instance when running a headless Emacs server.  Functions like
 instead. */);
   inhibit_interaction = 0;
 
+  DEFVAR_BOOL ("read-minibuffer-restore-windows", read_minibuffer_restore_windows,
+	       doc: /* Non-nil means restore window configurations on exit from minibuffer.
+If this is non-nil (the default), reading input with the minibuffer will
+restore, on exit, the window configurations of the frame where the
+minibuffer was entered from and, if it is different, the frame that owns
+the associated minibuffer window.  If this is nil, no such restorations
+are done.  */);
+  read_minibuffer_restore_windows = true;
+
   defsubr (&Sactive_minibuffer_window);
   defsubr (&Sset_minibuffer_window);
   defsubr (&Sread_from_minibuffer);